Is it possible to register "virtual" user/group IDs in a Linux system?

Is there a standardized mechanism in Linux which can be used to tie usernames to user IDs without actually creating a system account that can log in?

It would seem something like this is possible, given that there is the ability to connect to a Windows server and give UIDs to the users. Usually in a high number range.

What I need/want this for is to be able to assign meaningful names to groups and users that only exist as subordinate IDs (userns).